A disulphide bond is a covalent linkage between two sulfhydryl groups on the R groups of two cysteine residues on a polypeptide backbone. It can either be an inter- or intra-molecular bond. This type of linkage forms during the processing of the protein in the rough endoplasmic reticulum. The disulphide bond is responsible for the stability of the tertiary and quaternary structure of a majority of known proteins . This bonding is stronger than hydrogen bonding.
A disulphide bond is also called disulphide bridge. It is the name of the covalent bond that is formed when two thiol groups, SH groups, undergo oxidation and a bond forms between the two sulphur atoms. In the formation of this type of bond, two protons and two electrons are produced as biproducts.
Disulphide bonds are often present in tertiary protein structure between cysteine residues, as they help to stabilise the protein. The S-S bonds are formed as part of the folding of the protein into its final 3D structure in the Endoplasmic reticulum.
The disulphide bonds only occur on the extracellular domains of a protein, as in the Cytosol (a reducing environment) the bonds become unstable and break.
A disulphide bond is a covalent linkage formed between two sulfhydryl groups on cysteines. It is a common way to join two proteins or to link together different parts of the same protein in the extracellular space.